COMPOSITION OF NUCLEUS,CLASS12th PHYSICS

NUCLEUS(ATOMIC):

A  nucleus is composed of elementary particles protons and neutrons.An atom consist of central nucleus,containing entire positive charge and almost entire mass.The PROTON was discovered by RUTHERFORD by bombardment of Alpha particles on Nitrogen.

And the NEUTRON was discovered by J.CHADWICK by bombardment of Alpha particles on Beryllium.

PROTON:

It is a positively charged fundamental particle having rest mass 1.672×10-²⁷kg and having charge 1.6×10-¹⁹C.

NEUTRON:

 A neutron is a neutral particle or charge less particle having rest mass of 1.674×10-²⁷Kg.

NUCLEONS:

The particles which are present with in the nucleus (PROTONS & NEUTRONS) are collectively known as NUCLEONS.

A=ATOMIC MASS NUMBER

Atomic mass number is denoted by (A).

It is the total number of protons and neutrons present in a nucleus.

A=no of protons + no of neutrons

It is written as superscript(on the top) denoting the atomic mass number of a particular element.

Z=ATOMIC NUMBER

Atomic number is the number of protons  present in the nucleus.

It is denoted by (Z).

The subscripts(in the base) denotes the atomic number.

NUMBER OF NEUTRONS=(A - Z)

NUCLEAR MASS:

The total mass of the protons and the neutrons present in a nucleus is called the Nuclear Mass.